The present invention relates to an apparatus to automatically control the infusion rate or speed of a drip infusion system.
As a method of injecting a medical solution into a living body, a drip infusion system is well known, in which a medical solution contained in a medicine bottle in gravitationally infused into an object through an infusion tube provided at one end with an infusion needle, the tube connecting between the the bottle and the object with the needle thrusted into the body. Midway of the infusion tube there are provided in series a transparent drip chamber and a flow rate regulation clamp. The flow rate of the medical solution being infused is manually controlled with the clamp adjusted depending on intuition and experience in accordance with the size and frequency of droplets seen falling in the drip chamber. In spite of the fact that the speed of infusion is possibly an important factor in medical treatment, it is difficult or troublesome to obtain an optimum infusion condition by means of such a manual flow rate control made depending on intuition and experience. Further, it is inconvenient that the clamping is necessarily readjusted for a temperature variation, because the infusion speed depends on temperature through the temperature dependence of the viscosity and surface tension of the medical solution.